Dependence of Magnetic Hysteresis on Evolving Single-Sample Sintering in Fine-Grained Yttrium Iron Garnet

Abstract

Mono-dispersed yttrium iron garnet nanoparticles have been synthesized via mechanical alloying technique, and some attendant qualitative relationships between evolving microstructural parameters and magnetic properties have been clearly revealed. A rarely employed single-sample sintering scheme was adopted where only one sample was sintered repeatedly from 600 °C to 1400 °C prior to an analysis of evolution of microstructure-dependent magnetic properties after each sintering. A brief, yet detailed characterization of the sample was carried out using Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and B–H Hysteresis graph. A scrutiny of the B–H Hysteresis graph results showed a transition from disordered to ordered magnetism which belongs to three different magnetically dominant groups, namely weak ferro-, moderately strong ferro-, and strongly ferromagnetic groups. Three factors were found to strongly influence the ordered magnetism of the sample, namely the crystallinity degree of the crystalline phase, the number of grains with size larger than a critical diameter, and the number of large enough grains for magnetic order accommodation.